Fuel in oil

[moltarscott]

I have had this problem for a long time now. Fuel in the oil.

I have done many things to remedy the problem but nothing seems to work. I'll start you on this journey of mine with some info. I have a 1981 xs650 special with 30,000 miles on it.

I bought the bike hoping to turn it into a bobber/chopper of some sort and over the 2 years I have owned it I have done just that, with very little troubles except for the fact that throughout the entire time I've owned the bike it has leaked gas into the oil.

So here is what I have done so far. As a warning other changes were going on with the bike as time went on that might effect my problem but I'm not sure. I'll mention what i think is relevant. Also I replace the oil after each failure to fix the problem, also most times gas leaked into the oil while the bike was sitting over night. It was only ever the contents of the carbs never more than that each time.

- Bought bike and found gas in oil.
- cleaned carbs witch were dirty. still gas in oil.
- set float height to manual specs. still gas in oil.
- replaced floats, float needles and seats that the float needles sit in. still gas in oil.
- rebuilt petcocks and replaced fuel line. still gas in oil.
- changed out tank for a sportser tank and added manual petcock (on/off type) capped off air barbs. still gas in oil.

At this time I was doing some frame work and added 11" shocks which lowered the back end by about 3" or so. Not sure if that is relevant or not.

- completely rebuilt carbs i mean everything. also rejetted for new open pipes and air pods. still gas in oil.
- set the blasted float height so high that it barley let gas into the carbs basically making it not run. Got up the next morning gas in the oil again.
- parked it on a hill so that it was almost physically impossible for gas to run against gravity into the oil. next morning gas in the oil.
- disconnected fuel line from tank, pinch off fuel line so no air could get in. still gas in oil.

- bought new carbs from mikesxs. those 300.00 flatside carbs that come with new manifolds and pods. Replaced all fuel lines. took tank off and treated the inside for rust then resealed it with a lining kit. Rebuilt manual petcock just to be sure. At this point I was sure I had it beat. I even bought fancy $6 dollar oil from the motorcycle shop. I had also finished my chop of the bike with a new paint job. Was riding down the road and I noticed that the engine was whining a little bit and was a bit hot. pulled over and guess what GAS IN THE OIL.

OMG!

I'm not a mechanic by any means and my solution for most problems is to work harder at my job so I can afford to buy new stuff that will fix the problems. I have no problem throwing money at this thing to fix it. But I refuse to both pay a guy to fix it for me or to give up.

Please if any of you could find it in your hart to help me I would be so happy.

- Scott

p.s. added pic of the bike although it isn't recent.

 

[jamesgs4]

use one of these
http://www.motionpro.com/motorcycle/partno/12-0035/

how are you checking for gas? smell? volume difference?

 

[blackbetty]

You're focusing too much on the carbs, Gas in oil is usually indicative of worn rings.

Do a compression check and see if it's within spec...

 

[moltarscott]

use one of these
http://www.motionpro.com/motorcycle/partno/12-0035/

how are you checking for gas? smell? volume difference?

I have manual petcocks do I really need an inline fuel valve as well? The petcock isn't letting gas in the carbs at all when turned off. I am checking first by smell and then by visually checking the oil when I drain it. It only leaks what's in the carbs into the oil so volume isn't really noticeable right away.

 

[moltarscott]

You're focusing too much on the carbs, Gas in oil is usually indicative of worn rings.

Do a compression check and see if it's within spec...

I'm pretty amateur when it comes to engines, I mean I understand the basics but how do rings prevent gas from getting into the crankcase? I mean most times it hasn't even run in between oil changes, is that indicative of bad rings? I assume you mean piston rings.

Sry for my lack of knowledge but the only thing I've done to the engine is change a cam chain. pushrod bearings and clutch springs. :/

 

[jamesgs4]

how does the gas get from the bowls into the crankcase without the engine running? The valve I use is because the ethanol mix in my area swells my petcock seals and they always leak. Blackbetty is prob spot on about the rings being the source. My original '81engine trashed a right side crank bearing around 20k miles, possibly because I had gas in the oil a few times due to leaky petcocks and float needle housing o-rings.

 

[moltarscott]

I guess I'm about to get acquainted with my engine. So we are pretty sure it's the rings, I don't have a compression tester, should I go get one and do that first? What's the spec 150psi or so?

 

[jamesgs4]

A tester is a handy tool to have, so I would go ahead and grab one. did you change the o-rings in the float needle housing? those are notorious for leaking on these 81 carbs.

 

[blackbetty]

Look for a reading around 125psi, get a compression tester at auto zone for like $15.

Rings on a piston have a variety of functions, one of them being to hold compression in a cylinder when a piston is at top dead center on the compression stroke.....bad rings will let a little of the air/fuel mixture pass by the piston and into the crankcase.

I'd try and figure it out sooner than later, fuel will degrade oil down significantly and cause lots of other problems, especially with engines like ours that use ball bearings at the crank/cam etc.

Easy stuff don't be worried.

 

[moltarscott]

A tester is a handy tool to have, so I would go ahead and grab one. did you change the o-rings in the float needle housing? those are notorious for leaking on these 81 carbs.

Yeah I changed them on the BS34's and it didn't help. They aren't on the bike anymore because I got the "XS Performance Keihin Carb Kit" first item here http://www.xs650direct.com/products-82.html

 

[retiredgentleman]

Normal compression in these engines is 140 to 145 psi.

 

[WindLvr]

After you manually shut your fuel off with the petcock, do you let the bike run on what's left in the float bowl? Try that and see if you are still getting fuel in your oil. It might just be a slow drip going in there. If it was dumping in you would get vapor lock in your crankcase which would not even allow the enginee to turn over. I would say your rings are headed south if you absolutely sure your petcock isn't leaking and you are turning it to off.

 

[moltarscott]

After you manually shut your fuel off with the petcock, do you let the bike run on what's left in the float bowl? Try that and see if you are still getting fuel in your oil. It might just be a slow drip going in there. If it was dumping in you would get vapor lock in your crankcase which would not even allow the enginee to turn over. I would say your rings are headed south if you absolutely sure your petcock isn't leaking and you are turning it to off.

I haven't tried that. I'm sure it's not dumping fuel in it because I have a clear fuel filter and I can see that it doesn't flow when fuel is shut off or petcock disconnected. I'd say it takes about 8 - 12 hours of sitting for all the fuel from the carbs to get into the engine.

seems rings are my problem.

 

[gggGary]

First your dedication to this bike is awesome you are a true XS650 nut!
Now let's not leap to another conclusion. Rings no matter how bad won't let gas into the crank when the bike is just sitting unless something else is wrong.
If the rings are that bad you will have lots of blow by. The fitting at the top back of the head will be blowing air (and oil) when the engine is running.
They also will not dump gas in the crank when the bike is running unless compression is REALLY bad on at least one side. So yes go spend a few bucks on a compression tester. You won't regret it. The type with a hose is by far the best to get.
Something like this will do; http://www.harborfreight.com/compression-test-kit-66216.html

But really? I don't think that is your issue. Is the bike really sucking the float bowls dry? Open the drains in the morning, little gas is left in the float bowls? Any chance of a larger picture of the carb area of your bike. Any other "non standard" changes you might have made to the bike? You have a lot of friends here, we all want you to be able to enjoy your bike.

 

[gggGary]

What do your plugs look like when you pull them. Just speculating here. Your air filters look like good ones and appear well oiled. Have you always used oiled filters? I am looking for something that has not changed in spite of all the things you have done to fix this problem. Are you keeping the bike in that shed? Where in the country are you located? Does your Sportster tank have proper venting? there is an issue with matching tanks and vented (or not) caps.

 

[ReycleBill]

I haven't tried that. I'm sure it's not dumping fuel in it because I have a clear fuel filter and I can see that it doesn't flow when fuel is shut off or petcock disconnected. I'd say it takes about 8 - 12 hours of sitting for all the fuel from the carbs to get into the engine.

seems rings are my problem.

Like others have noted, bad rings and any other problem won't cause gas to get in the oil if gas isn't getting past the petcock(s).

Are you closing you petcocks when the bike isn't running? Every time even if only for a minute.

Do you have a vacuum operated petcock? If yes then you cannot cut it off as there is no off. On, Reserve and Prime but no off. If you have a vacuum petcock then what you think is off is actually prime and it will dump gas straight into the carbs even faster than being in the on position. Prime is only to be used in starting the engine after the float bowls have been drained or the fuel has evaporated from the bowls.

If yes, then I would start by rebuilding or replacing the petcocks. If not then close both petcocks every time you park even if only for a minute. The float bowls don't hold a lot of fuel and you would probably never be able to detect the content of the float bowls in the oil if it only happened one night. What you're probably detecting is drainage/leakage over the course of several days.

Park your bike on the center stand or on a block that will keep it level and let it sit for 10-15 minutes. Make sure the petcocks are closed. Then check the oil level and make note of the level. Leave the bike turned off and petcocks closed. Leave it on the center stand or block. Come back the next day and check the oil level. Has it gone up? If not then gas isn't running into the engine.

Smelling the oil will fool you as the residue smell of gas can stay in the oil for weeks after you've drained and refilled the oil. The only way to quickly get all the gas smell out of the oil is to leave the oil cap off the bike and leaving the oil cap off is not a good idea. Eventually, if the problem is fixed, the gas smell will go away but a quick drain and refill won't get it all out.

Where are you buying gasoline? Find out if you're buying Gasohol, E-85 or some other form of gasoline that contains any form of alcohol as alcohol will destroy many of the fuel system parts on these and most older bikes. Do not add any fuel additives to your gasoline as many if not most fuel additives contain alcohol.

PS. Love those pipes, I'm running the exact same thing. But they are a pain in the butt to keep tightened up.

 

[moltarscott]

First your dedication to this bike is awesome you are a true XS650 nut!
Now let's not leap to another conclusion. Rings no matter how bad won't let gas into the crank when the bike is just sitting unless something else is wrong.
If the rings are that bad you will have lots of blow by. The fitting at the top back of the head will be blowing air (and oil) when the engine is running.
They also will not dump gas in the crank when the bike is running unless compression is REALLY bad on at least one side. So yes go spend a few bucks on a compression tester. You won't regret it. The type with a hose is by far the best to get.
Something like this will do; http://www.harborfreight.com/compression-test-kit-66216.html

But really? I don't think that is your issue. Is the bike really sucking the float bowls dry? Open the drains in the morning, little gas is left in the float bowls? Any chance of a larger picture of the carb area of your bike. Any other "non standard" changes you might have made to the bike? You have a lot of friends here, we all want you to be able to enjoy your bike.

The only gas that is left in the the morning is a bit in the fuel lines as far as I can tell. If I drain the carbs without turning on the petcock about 1/2 of a shot glass comes out of each. so like 1 oz total.

new tank (cleaned and sealed inside), manual petcock (on/off/reserve) which doesn't leak a drip when disconnected, brand new carbs, brand new boots, brand new pods, aftermarket pipes, new coil and plug wires, hotter plugs, new cam chain, lowered in the rear by about 3" or so.

That's about all i've changed with the fuel/engine/exhaust. I really thought it was my float height that was the problem (because it is so low in the back which would make the floats not seat with standard float height). But I drastically changed floats height both ways on the BS34's that were on the bike with no change. (I also rebuit them completely so that rules out bad seals/needles).

close up of carbs

 

[moltarscott]

What do your plugs look like when you pull them. Just speculating here. Your air filters look like good ones and appear well oiled. Have you always used oiled filters? I am looking for something that has not changed in spite of all the things you have done to fix this problem. Are you keeping the bike in that shed? Where in the country are you located? Does your Sportster tank have proper venting? there is an issue with matching tanks and vented (or not) caps.

plugs are black and also foul a lot. I never could get the old bs34's to run right, I haven't tuned these new carbs up yet frankly because I don't want to drive around with gas in the oil. But they are good at idle, i just need to drop down the main jet and maybe a needle position. The filters are brand new and so were my old ones, also well taken care of.

The bike is kept outside most days but I roll it into the shed to work on or if it rains.

I'm located in Canada actually, nova scotia, sea level, mild but humid weather. Tank is non vented i think, I had the Harley dealership fit the petcock and gas cap for me as they know more about Harley's than I. I have left the cap off Over night a few times and Still had the carbs emptying themselves so I thought I ruled venting out.

 

[moltarscott]

Like others have noted, bad rings and any other problem won't cause gas to get in the oil if gas isn't getting past the petcock(s).

Are you closing you petcocks when the bike isn't running? Every time even if only for a minute.

Do you have a vacuum operated petcock? If yes then you cannot cut it off as there is no off. On, Reserve and Prime but no off. If you have a vacuum petcock then what you think is off is actually prime and it will dump gas straight into the carbs even faster than being in the on position. Prime is only to be used in starting the engine after the float bowls have been drained or the fuel has evaporated from the bowls.

If yes, then I would start by rebuilding or replacing the petcocks. If not then close both petcocks every time you park even if only for a minute. The float bowls don't hold a lot of fuel and you would probably never be able to detect the content of the float bowls in the oil if it only happened one night. What you're probably detecting is drainage/leakage over the course of several days.

Park your bike on the center stand or on a block that will keep it level and let it sit for 10-15 minutes. Make sure the petcocks are closed. Then check the oil level and make note of the level. Leave the bike turned off and petcocks closed. Leave it on the center stand or block. Come back the next day and check the oil level. Has it gone up? If not then gas isn't running into the engine.

Smelling the oil will fool you as the residue smell of gas can stay in the oil for weeks after you've drained and refilled the oil. The only way to quickly get all the gas smell out of the oil is to leave the oil cap off the bike and leaving the oil cap off is not a good idea. Eventually, if the problem is fixed, the gas smell will go away but a quick drain and refill won't get it all out.

Where are you buying gasoline? Find out if you're buying Gasohol, E-85 or some other form of gasoline that contains any form of alcohol as alcohol will destroy many of the fuel system parts on these and most older bikes. Do not add any fuel additives to your gasoline as many if not most fuel additives contain alcohol.

PS. Love those pipes, I'm running the exact same thing. But they are a pain in the butt to keep tightened up.

I'm closing the petcocks every time for sure.

I have manual petcocks (on/off/reserve).

As far as amount of gas in the oil it is relative to how many times I fill the carbs up. If I don't touch the bike for 7 days then I only have what was in the carbs in the oil. If I let the carbs fill up once every day for 7 days then I have 7 carbs full of gas in the oil.

I know it's a serious amount of gas in the oil because if I use the bike for one week every day and the end of the week when I change the oil it smells of gas and is very viscous. I guess it could be less than I think because I don't normally noticed a huge volume difference. Maybe 100-200cc after 7 days, but I do know that my engine whines pretty bad if I try and run it on the 8th day with that much gas in the oil.


yeah I love these pipes to and I have the same problem with air leaks with them, I used some carbon gasket stuff the try and seal them but the bike shook them out.

 

[moltarscott]

Going to get a compression tester today and about 30 quarts of oil

will see what I can find out.

thanks guys keep the ideas coming